6810 SRAM Chip

GND --- 1 U
------
24 --- VCC
D0 <-> 2 23 <-- A0
D1 <-> 3 22 <-- A1
D2 <-> 4 21 <-- A2
D3 <-> 5 20 <-- A3
D4 <-> 6 19 <-- A4
D5 <-> 7 18 <-- A5
D6 <-> 8 17 <-- A6
D7 <-> 9 16 <-- R/!W
CS0 --> 10 15 <-- !CS5
!CS1 --> 11 14 <-- !CS4
!CS --> 12 13 <-- !CS3

Quite rare these days: easier to get an ordinary JEDEC pinout RAM chip and wire up an adapter board.